Wellhead closure



June 15, 1965 o ETAL 3,189,099

WELLHEAD CLOSURE Filed June 2'7, 1962 5 Sheets-Sheet 2 INVENTORS IR AGENT June 1965 G. OTTEMAN ETAL 3,189,099

WELLHEAD CLOSURE 5 Sheets-Sheet 3 Filed June 27, 1962 FIG.4

INVE NTQRS L. G. OTTEMAN N. B. NEWMAN BY- H1604? HEIR AGENT United States Patent 3,139,6999 WELLHEAD QLOSURE Lloyd G. Gtteman and Nicholas R. Newman, Houston, Tex., assignors to Shell Oil Company, New York, N.Y., a corporation of Delaware Filed June 27, 1962, Ser. No. 205,535 2 (Ilaims. (Cl. 16666.5)

The apparatus relates to equipment used on oil and gas wells, and pertains more particularly to a wellhead closure apparatus adapted to close the open top of an underwater wellhead which may be positioned on the ocean floor.

The present invention is particularly concerned with a wellhead closure apparatus for use in closing a wellhead assembly positioned underwater where equipment is subject to the coorosive action of sea water as well as to the accumulation of various types of marine growth on equipment after prolonged exposure to the sea water. A copending application, serial No. 830,587, filed July 30, 1959, now abandoned, and entitled Underwater Well Completion Method, described a method for drilling and completing wells underwater at a offshore location by use of a marine conductor tube, extending from the surface of the water to the underwater wellhead, through which drilling and completion operations are carried out from a remote operational station or vessel positioned on or above the surface of the water. After installing the wellhead equipment on a completed well, the top of the production wellhead assembly is closed in a suitable manner, as by means of a lubricator and a wellhead closure apparatus in accordance with the present invention.

It is desirable to close underwater wells in a manner such that all possibility of any corrosion of the equipment is eliminated. One suitable method of accomplishing this is to inject a material, such as an oil or grease, into voids in a wellhead assembly as Well as between all metal parts which may be disconnected or moved at a later date. The protective material used is preferably a. fairly viscous material to which have been added one or more materials such as agents which inhibit the corrosion of metals and the growth of .marine life on the metal surface, etc.

It is therefore an object of the present invention to provide an apparatus which may be employed to force a lubricating material, such as grease, into the voids of a wellhead assembly.

A further object of the present invention is to provide apparatus adapted to form a fluid tight seal at the top of a wellhead assembly, or a related wellhead member.

Another object of the present invention is to provide a wellhead closure member of rugged design and construction which is not readily injured by the rough handling encountered during the completion of a well at an offshore location.

A further object of the present invention is to provide a wellhead closure member adapted to be installed in or removed from an underwater wellhead assembly by operations carried out from a remote location such as a vessel on the surface of the water.

These and other objects of the invention will be understood from the following description taken with regard to the drawing wherein:

FIGURE 1 is a diagrammatic view taken in longitudinal projection and illustrating a vessel positioned over an underwater wellhead assembly;

FIGURES 2 and 2A are the left and right hand portions of the wellhead closure apparatus of the present invention, taken in longitudinal cross section, and shown as being positioned to close the top of the wellhead,

ice

FIGURE 2 showing a latching element in an operative or locked position while FIGURE 2A shows the latching element in an inoperative or unlocked position; and

FIGURE 3 is a longitudinal cross section view of one form of a running tool for installing the wellhead closure member of the present invention in the top of the wellhead.

FIGURE 4 is a longitudinal view, taken in cross section, of another form of a closure plug of the present invention.

Referring to FIGURE 1 of the drawing, a drilling or workover platform or vessel 11 of any suitable floatable type is illustrated as fioating on the surface of a body of water 12 and substantially fixedly positioned over an underwater wellhead assembly generally represented by numeral 13. The vessel 11 may be substantially fixedly positioned in any siutable manner well known to the art or may be anchored in place. Equipment of this type may be used when carrying on well drilling operations in water depths varying from about to 1500 feet or more. The drilling vessel is equipped with a suitable derrick 14 as well as other auxiliary equipment needed during the drilling or working over of a Well. The derrick 16 is positioned over a drilling slot or well 15 which extends vertically through the barge in a conventional manner. When using the equipment of the present invention a slot of the vessel 11 may be either centrally located or extended in from an edge, However, drilling operations may be carried out over the side of the vessel without the use of a slot.

A typical underwater Wellhead structure 13 is illustrated as comprising a base member 16 which is positioned on the ocean floor 17 and is fixedly secured to a conductor pipe or large-diameter Well casing 18 which extends into a well, which has been previously drilled, and is preferably cemented therein. If desired, the underwater wellhead assembly 13 may be provided with suitable guide means for guiding equipment from the vessel 11 at the surface down to the wellhead assembly on the ocean floor. In the arrangement shown, the wellhead assembly is provided with a pair of guide columns 20 and 21 having guide cables 22 and 23 extending thereinto and fixedly secured to the lower ends of the columns. The upper ends of the guide cables 22 and 23 are preferably secured to the vessel 11 by constant tension hoists 24 and 25. A suitable carriage such for example as guide arms as and 27 are arranged to slide on the vertically extending guide cable 22 and 23 so as to bring a tool, for example a running tool 28, into register with a certain portion of the wellhead assembly 13. The running tool 28 is generally lowered through the Water by being secured to the lower end of a running pipe string 30 which is generally a small-diameter pipe string.

The top of the wellhead assembly 13 (FIGURE 1) may be provided with a lubricator head 31 into which the wellhead closure apparatus 32 of the present invention may be inserted.

In FIGURE 2A the wellhead closure apparatus 32 of the present invention is illustrated as comprising body member 33 whose lower end is of a diameter to fit within the bore 34 of the lubricator head 31, or in the bore of any other wellhead member to be closed by the wellhead closure apparatus 32 of the present invention. Formed in the inner wall of the lubricator head 31 is a suitable recess, preferably in the form of an annular groove. The groove 35 is adapted to receive a plurality of latching elements 36 which are spring-loaded, as by being secured to downwardly extending, spring-like collet fingers 37 which are fixed secured at the top thereof, as at 38 to the body member 33. Thus, it may be seen that the latch elements 36 are in their normal position so that they extend beyond the outer surface of the body member 33 and into the locking groove 35 of the lubricator head. From the arrangement illustrated it is only possible for the latching elements 36 to move inwardly toward the axis of the closure body member 33 when they are retracted out of the groove 35.

For ease of illustration only one latching element has been shown in FIGURES 2 and 2A, although it is to be understood that a greater number are preferred and are normally equally spaced around the circumference of the body member 33. To facilitate the alignment of the latching elements 36 in the locking groove 35, the body member 33 is preferably provided with an outwardlyextending seating shoulder which may be in the form of an upwardly-bevelled flange 40 or a series of individual lugs of the same cross section positioned around the periphery of the body member 33. The seating shoulder flange 40 is spaced from the latching elements 36 so as to engage the landing surface 41 at the top of the lubricator head 31 when the latching elements 36 are in register with the locking groove 35. Additionally, a partially recessed seal, such for example as an O-ring seal 42 is carried on the outer surface of the body member 33 for sealing between the body member 33 and the inner surface of the lubricator head 31.

Extending upwardly from the top of the body member 33 are telescoping concentric rod elements or tubular members 44 and 45. The outer rod element 45 is provided with a fishing head 46 near the top thereof by which the wellhead closure apparatus can be withdrawn from the top of a well. The outer rod element or tubular member 45 is open at its upper end 47 while the upper end of inner rod element or tubular member 44 is closed by a plug 48. Just below the plug 48 the inner rod element is provided with one or more fluid ports 50 through the wall thereof which are in communication with the bore 51. A spring-loaded check valve 52 normally closes the bore 51 against the escape of fluid from the well. Seals 53 and 54 are provided between the inner and outer rod elements 44 and 45, respectively. A stop element in the form of an outwardly-extending flange 55 formed on the outer surface of the inner rod element 44 is adapted to cooperate and land on a stop element 56 carried within the body member 53 for limiting the downward movement of the inner rod element relative to the outer element. At the end of the downward stroke of the inner rod element 44 when the stop elements 55 and 56 are in contact, a latch blocking device, which may be in the form of an annular flange or piston 57, is positioned substantially in back of the latch elements 36 as shown in FIGURE 2. Since the top of the well is filled with fluid, preferably oil or grease, at the time the closure apparatus is to be inserted therein, fluid ports 58 are provided in the piston 57 for transferring fluid from one side of the piston to the other as the piston 57 moves downwardly within the body member 33. The top of the body member 33 is provided with one or more check valves 60 so as to permit the escape of fluid to the outside of the plug or closure apparatus 32. Valves 60 may be high pressure relief valves to seal the well against escape of fluid below a selected pressure.

The bore 61 of the outer rod element or tubular member 45 is enlarged in diameter, as at 62, to form a flow passage, as shown in FIGURE 2, permitting the flow of fluid from the bore 61 into its enlarged portion 62 and thence through the fluid port 50 and past the check valve 52 and into the top of the wellhead closure assembly so that a lubricant or corrosion inhibitor can be circulated into the well through the running string 30 and running tool 28. One or more shear pins 63 are employed to secure the body member 33 to the outer tubular member 45. If desired, one or more locking dogs 64 may be pivotally mounted on the lower end of outer tubular member 45 for engaging the top of the stop element 55 or the recess 65 formed thereabove on the inner 4 tubular member 44, as shown in FIGURE 2, when the inner tubular member 44 is at the lower end of its stroke. Alternatively, a split ring could be employed in a manner well known to the art.

While the wellhead closure member of the present invention may be inserted into the top of a wellhead assembly in many ways and by many different apparatuses, one form of a running tool is illustrated in FIGURE 3 which is adapted to be secured to the fishing head 46 of the wellhead closure apparatus and lowered at the end of a running string 30. The running tool comprises a body member having a downwardly-extending sleeve 71 slidably mounted on the outer surface thereof and normally maintained in an extended position by a compression spring 72. Secured to the lower end of the body member 7 0 are a plurality of spring-loaded latching elements or collet fingers 72a which spring outwardly to a normal position and are contained in their retracted position, as illustrated, by the lower end of the sleeve element 71. The inner shoulder 73 of the collet fingers 72 is adapted to engage the fishing head 46 (FIGURES 2 and 2A) of the wellhead closure apparatus 32. Fluid ports 74 extend through the wall of the body member 70 just below the top of the slidable sleeve 71 so as to terminate at the inner face 75 thereof whereby fluid pressure will move the sleeve upwardly against the action of the spring 72 and allow the collet fingers and latching element 72 to expand and release the fishing head of the wellhead closure element, when desired. The bore 76 of the body member 70 is provided with a sleeve valve 77 having a bore 78 therethrough that is adapted to be closed by means of a ball 80. The wire retainer split ring 81 limits the upward movement of the sleeve valve 77 while a shoulder 82 limits its downward movement. A downwardly-extending nipple 83 is slidably mounted within a downwardly-extending tubular portion 84 of the apparatus and maintained in its seated position by a compression spring 85 which also acts to hold the sleeve valve in its uppermost position. The lower end of the nipple 83 is provided with a gasket or other sealing member 86 and is adapted to seal in a fluid tight manner against the upper edge 47 (FIGURE 2A) of the outer rod element or tubular member 45. A check valve 87 is provided through the wall of the sleeve valve 77 to allow any fluid trapped therein to escape back into the bore of the sleeve valve.

The running tool described hereinbefore with regard to FIGURE 3 is attached to the fishing head of the wellhead closure apparatus of the present invention by inserting the fishing head 46 of the wellhead closure into the bottom of the running tool 28. This is done by pulling the sleeve 71 upwardly so that the collet fingers 72 spring outwardly allowing the fishing head 46 to enter. When the outer sleeve 71 of the running tool is allowed to snap downwardly again under spring pressure, the collet fingers 72 are wedged under the fishing head 46 of the closure member in the upper end 47 of the outer tubular member 45 and is pressed in a fluid type manner against the seal 86 (FIGURE 3) of the downwardly extending nipple 83. The running tool is then secured to the lower end of the running string 30 so that it may be run down through the water from the vessel to the wellhead at the ocean floor.

When the running tool and wellhead closure are being lowered through the water to the wellhead, they are in the position shown in FIGURES 3 and 2A respectively except that the ball 80 (FIGURE 3) is not in place. The lower faces of the collet fingers 36 (FIGURES 2 and 2A) are illustrated as being tapered at about an angle of 45 but a substantially greater angle to the horizontal or a slightly lesser angle may be employed depending upon the weight of the wellhead closure (which may be as much as lbs.), the weight of the running string 30 and the flexibility of the spring element 37. The upper faces of the latching elements 36 are formed having a substantially lesser angle say from to about 30 from the horizontal so that it takes a substantial force, say 5000 lbs., to pull the wellhead closure out of the well. At least a slight angle is necessary and should be sufiiciently great so that the latching elements do not break off and fall down into the well when the wellhead closure is pulled therefrom.

As the wellhead closure is forced into the top of the lubricator head 31 (FIGURE 2A) the latching elements 36 first contact the landing surface 41 and are forced inwardly into the body member 33 until they can snap out in the locking groove 35. Fluid under pressure is then pumped down through the running string 30 and into the bore 61 of the outer tubular element 45 at the top of the wellhead closure, thus applying fluid pressure against the closure plug 48 at the top of the inner tubular member 44 causing the latter to be forced downwardly together with the latch-blocking piston 57 which slides down and back of the spring element 37 to be positioned in back of the latching element 36 as shown in FIGURE 2. At this time the locking dogs 64 will snap into the recesses 65 and lock the locking piston 57 in place while fluid under pressure within the bore 61 of the outer tubular element 45 will pass down the enlarged portions 62 thereof through the ports 50 and down the bore 51 of the inner tubular member 44 to escape upwardly out ports 58 and check valves 60. The subsequent dropping of ball 80 and the continued application of fluid pressure will cause sleeve 71 to move upwardly and release the latch fingers 72 from the fishing head 46.

In the event that the locking dogs 64 and shear pins 63 are employed, upon running a fishing head or retrieving tool down to the well and engaging the fishing head 46 of the wellhead closure, by exerting an upward pull on the running string or fishing string the pin 63 will shear allowing the inner and outer tubular members 44 and 45 to be drawn upwardly along with the latch blocking piston 57 so that a continued and increased pull on the fishing string will cause the latches 36 to spring inwardly out of the locking groove 35 so that the wellhead closure member 32 can be withdrawn from the top of the lubricator 31 and pulled back to the vessel on the surface.

Another closure plug adapted to seat on landing surface 141 is shown in FIGURE 4 as comprising a body member 133 having a seating shoulder flange 140, annular seal 142 and check valves 152 and 160 similar to those employed in the arrangement of FIGURES 2 and 2A. The latching dogs or elements 136 are normally urged to their extended position, as illustrated, by horizontally extcndible compression springs 137 which are contained within recesses 134 of the body member 133. The recesses 134 are of a size so that the latching dogs 135 can be entirely retracted therein when the closure plug is being inserted into or withdrawn from its latched position in latching groove 135.

We claim as our invention:

1. A remotely positionable and removable wellhead bore closure apparatus adapted to close in a fluidtight manner the bore at the top of a tubular production wellhead in a fluidtight manner, said bore closure apparatus comprising a plug-like body member of a size to operatively engage and close the open top of a tubular wellhead having locking recess means formed in the adjacent wall thereof,

spring-loaded latch means carried by said body member and normally extending beyond the outer surface thereof, said latch means being of a size to seat within the recess means in the wall of said wellhead,

sealing means carried on the outer surface of said body member for establishing a fluidtight seal between said body member and said wellhead,

camming surfaces formed on the upper and lower faces of those portions of said spring-loaded latch means extending outwardly beyond the outer surface of said body member whereby said latch means are cammed into said body member by a force applied to said camming surfaces,

fishing head means secured to a portion of rod means slidingly movable through the top of said body member and latch-blocking means secured to the other end of said rod means and adapted to be slidably positioned in back of said latch means to prevent movement to said latch means to an inoperative position,

said latch-blocking means being provided with fluid port means theretbrough in a direction to permit passage of fluid in a general direction which is substantially parallel to the axis of said body member, and

check valve means through the top of said body member to permit the escape of fluid from the inside thereof.

2. A remotely positionable and removable wellhead bore closure apparatus adapted to close in a fluidtight manner the bore at the top of a tubular production wellhead in a fluidtight manner, said bore closure apparatus comprising a plug-like body member of a size to operatively engage and close the open top of a tubular wellhead having locking recess means formed in the adjacent wall thereof,

spring-loaded latch means carried by said body mem ber and normally extending beyond the outer surface thereof, said latch means being of a size to seat within the recess means in the wall of said wellhead. sealing means carried on the outer surface of said body member for establishing a fluidtight seal between said body member and said wellhead,

camming surfaces formed on the upper and lower faces of those portions of said spring-loaded latch means extending beyond the outer surface of said body member whereby said latch means are cammed into said body member by a force applied to said camming surfaces,

fishing head means secured to a portion of rod means slidingly movable through the top of said body member and latch-blocking means secured to the other end of said rod means and adapted to be slidably positioned in back of said latch means to prevent movement to said latch means to an inoperative position,

and locking means carried by said body member engageable with the slidable rod means thereof for locking said rod against movement when the latchblocking means are positioned in back of said latch means.

References Cited by the Examiner UNITED STATES PATENTS 428,442' 5/90 Skinner 166-95 X 651,679 6/00' Tait 166---95 X 1,735,330 11/29 McMahan 16695 1,835,418 12/31 McHardy 16685 X 1,888,621 11/32 Collins 16679 2,392,244 1/46 Hooser 166-136 X 2,475,748 7/49 LeRoy 13890 2,779,420 1/57 Stevenson 166136 X 2,901,045 8/59 Schramm 166-492 X 2,962,096 11/60 Knox 16675 3,071,188 1/63 Raulins 166-75 X CHARLES E. OCONNELL, Primary Examiner. 

1. A REMOTELY POSITIONABLE AND REMOVABLE WELLHEAD BORE CLOSURE APPARATUS ADAPTED TO CLOSE IN A FLUIDTIGHT MANNER THE BORE AT THE TOP OF A TUBULAR PRODUCTION WELLHEAD IN A FLUIDTIGHT MANNER, SAID BORE CLOSURE APPARATUS COMPRISING A PLUNGER-LIKE BODY MEMBER OF A SIZE TO OPERATIVELY ENGAGE AND CLOSE THE OPEN TOP OF A TUBULAR WELLHEAD HAVING LOCKING RECESS MEANS FORMED IN THE ADJACENT WALL THEREOF, SPRING-LOADED LATCH MEANS CARRIED BY SAID BODY MEMBER AND NORMALLY EXTENDING BEYOND THE OUTER SURFACE THEREOF, SAID LATCH MEANS BEING OF A SIZE TO SEAT WITHIN THE RECESS MEANS IN THE WALL OF SAID WELLHEAD, SEALING MEANS CARRIED ON THE OUTER SURFACE OF SAID BODY MEMBER FOR ESTABLISHING A FLUIDTIGHT SEAL BETWEEN SAID BODY MEMBER AND SEAL WELLHEAD, CAMMING SURFACES FORMED ON THE UPPER AND LOWER FACES OF THOSE PORTIONS OF SAID SPRING-LOADED LATCH MEANS EXTENDING OUTWARDLY BEYOND THE OUTER SUR- 